The lifted structure (LS) loss [1]} tries to push a pair of samples belonging to ane class away from all the samples belonging to some different class. It is formulated as:
\(\mathcal {L}_{LS}=\frac{1}{|\mathcal {P}|}\sum _{(i,j)\in \mathcal {P}}\bigg [d_{i,j}+m-\nonumber \\\min \left(\min _{\mathbf {c}[i]\ne \mathbf {c}[k]}d_{i,k},\min _{\mathbf {c}[j]\ne \mathbf {c}[l]}d_{j,l}\right)\bigg ]_+.\) 
